In cold weather it is usually necessary to preheat an aircraft internal combustion engine exposed to the low temperature in order to facilitate starting. Without preheating, starting the engine under such circumstances is difficult and, even if starting is accomplished, it can be harmful to the cold engine components.
A common method of preheating an aircraft engine involves blowing hot air into the engine compartment. Apparatus to accomplish this includes portable combustion heaters and portable electric heaters with fans. These systems are inconvenient and are not very portable and not an integral part of the engine whereby they may accompany the aircraft. These systems may also expose the aircraft to undue fire hazzard.
An aircraft engine preheating apparatus is described in U.S. Pat. No. 3,953,707 issued Apr. 27, 1976 to Tanis. That patent describes an electric heating element constructed to fit in the thermocouple holes of the cylinder heads of aircraft engines which are normally not fitted with thermocouples for more than one cylinder head. However, for those engines not equipped with such thermocouple holes, mounting holes must be specially drilled in each cylinder head.